Voltage regulators, for example DC-DC converters, supply a stable power source to an electronic system. Voltage regulators are typically designed to maintain terminal voltage sources within specified limits even in variable input voltage and/or load conditions. Voltage regulators are typically susceptible to faults or failures, which can cause the output voltage of the regulator to go outside a suitable range during a fault. A fault in the voltage regulator can damage a device using the regulated DC voltage or render the device unusable.
A fault may not be detected until the affected voltage regulator is out of tolerance as determined by a fault detection device that monitors the output voltage of the regulator. To avoid catastrophic failure of the system, redundant voltage regulators can be used to ensure reliability, coupled in parallel to a load device so that if one voltage regulator fails, another continues to maintain a stable supply voltage.
Typically the redundant voltage regulators are connected at an output voltage rail. To isolate the parallel-connected voltage regulators for fault tolerance, a diode can be connected between the individual voltage regulators and the rail. However, an OR-connection of the diodes to isolate a faulty voltage converter can decrease system efficiency due to the finite voltage drop of the diodes and can prevent suitable dynamic load performance.
The difficulties in making the parallel connection of redundant voltage regulators can be avoided by detecting faults and disabling a faulty regulator before the output voltage goes out of regulation.